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最近需要将H264视频编码成MP4格式。研究了一下,一种方法是采用ffmpeg库,可以先将H264文件解码,再编码生成MP4文件,但这种方式效率较低,10M的视频可能需要几秒钟才能完成。另一种方式根据MP4文件协议直接将H264包封装成MP4格式,由于是直接基于MP4的封装,因而效率很高。H264可以很方便的封装成FLV文件,但MP4格式格式相对比较复杂,封装起来会比较麻烦。由于没时间研究MP4协议,在Google Code上找到一个开源的MP4编解码库Mp4v2(https://code.google.com/p/mp4v2/),通过Mp4v2可以很方便的将H264编码成MP4格式文件。为了方便使用,基于该库封装了一个MP4Encoder类,MP4Encoder封装的接口如下。目前仅支持将H264文件或数据帧编码成MP4文件。
- class MP4Encoder
- {
- public:
- MP4Encoder(void);
- ~MP4Encoder(void);
- public:
- // open or creat a mp4 file.
- MP4FileHandle CreateMP4File(const char *fileName,int width,int height,int timeScale = 90000,int frameRate = 25);
- // wirte 264 metadata in mp4 file.
- bool Write264Metadata(MP4FileHandle hMp4File,LPMP4ENC_Metadata lpMetadata);
- // wirte 264 data, data can contain multiple frame.
- int WriteH264Data(MP4FileHandle hMp4File,const unsigned char* pData,int size);
- // close mp4 file.
- void CloseMP4File(MP4FileHandle hMp4File);
- // convert H264 file to mp4 file.
- // no need to call CreateMP4File and CloseMP4File,it will create/close mp4 file automaticly.
- bool WriteH264File(const char* pFile264,const char* pFileMp4);
- // Prase H264 metamata from H264 data frame
- static bool PraseMetadata(const unsigned char* pData,int size,MP4ENC_Metadata &metadata);
- };
客户端调用示例代码:
- #include <stdio.h>
- #include "MP4Encoder\MP4Encoder.h"
- int main(int argc, char** argv)
- {
- MP4Encoder mp4Encoder;
- // convert H264 file to mp4 file
- mp4Encoder.WriteH264File("test.264","test.mp4");
- }
MP4Encoder完整的代码如下:
- /********************************************************************
- filename: MP4Encoder.h
- created: 2013-04-16
- author: firehood
- purpose: MP4编码器,基于开源库mp4v2实现(https://code.google.com/p/mp4v2/)。
- *********************************************************************/
- #pragma once
- #include "mp4v2\mp4v2.h"
- // NALU单元
- typedef struct _MP4ENC_NaluUnit
- {
- int type;
- int size;
- unsigned char *data;
- }MP4ENC_NaluUnit;
- typedef struct _MP4ENC_Metadata
- {
- // video, must be h264 type
- unsigned int nSpsLen;
- unsigned char Sps[1024];
- unsigned int nPpsLen;
- unsigned char Pps[1024];
- } MP4ENC_Metadata,*LPMP4ENC_Metadata;
- class MP4Encoder
- {
- public:
- MP4Encoder(void);
- ~MP4Encoder(void);
- public:
- // open or creat a mp4 file.
- MP4FileHandle CreateMP4File(const char *fileName,int width,int height,int timeScale = 90000,int frameRate = 25);
- // wirte 264 metadata in mp4 file.
- bool Write264Metadata(MP4FileHandle hMp4File,LPMP4ENC_Metadata lpMetadata);
- // wirte 264 data, data can contain multiple frame.
- int WriteH264Data(MP4FileHandle hMp4File,const unsigned char* pData,int size);
- // close mp4 file.
- void CloseMP4File(MP4FileHandle hMp4File);
- // convert H264 file to mp4 file.
- // no need to call CreateMP4File and CloseMP4File,it will create/close mp4 file automaticly.
- bool WriteH264File(const char* pFile264,const char* pFileMp4);
- // Prase H264 metamata from H264 data frame
- static bool PraseMetadata(const unsigned char* pData,int size,MP4ENC_Metadata &metadata);
- private:
- // read one nalu from H264 data buffer
- static int ReadOneNaluFromBuf(const unsigned char *buffer,unsigned int nBufferSize,unsigned int offSet,MP4ENC_NaluUnit &nalu);
- private:
- int m_nWidth;
- int m_nHeight;
- int m_nFrameRate;
- int m_nTimeScale;
- MP4TrackId m_videoId;
- };
MP4Encoder.cpp
- /********************************************************************
- filename: MP4Encoder.cpp
- created: 2013-04-16
- author: firehood
- purpose: MP4编码器,基于开源库mp4v2实现(https://code.google.com/p/mp4v2/)。
- *********************************************************************/
- #include "MP4Encoder.h"
- #include <string.h>
- #define BUFFER_SIZE (1024*1024)
- MP4Encoder::MP4Encoder(void):
- m_videoId(NULL),
- m_nWidth(0),
- m_nHeight(0),
- m_nTimeScale(0),
- m_nFrameRate(0)
- {
- }
- MP4Encoder::~MP4Encoder(void)
- {
- }
- MP4FileHandle MP4Encoder::CreateMP4File(const char *pFileName,int width,int height,int timeScale/* = 90000*/,int frameRate/* = 25*/)
- {
- if(pFileName == NULL)
- {
- return false;
- }
- // create mp4 file
- MP4FileHandle hMp4file = MP4Create(pFileName);
- if (hMp4file == MP4_INVALID_FILE_HANDLE)
- {
- printf("ERROR:Open file fialed.\n");
- return false;
- }
- m_nWidth = width;
- m_nHeight = height;
- m_nTimeScale = 90000;
- m_nFrameRate = 25;
- MP4SetTimeScale(hMp4file, m_nTimeScale);
- return hMp4file;
- }
- bool MP4Encoder::Write264Metadata(MP4FileHandle hMp4File,LPMP4ENC_Metadata lpMetadata)
- {
- m_videoId = MP4AddH264VideoTrack
- (hMp4File,
- m_nTimeScale,
- m_nTimeScale / m_nFrameRate,
- m_nWidth, // width
- m_nHeight,// height
- lpMetadata->Sps[1], // sps[1] AVCProfileIndication
- lpMetadata->Sps[2], // sps[2] profile_compat
- lpMetadata->Sps[3], // sps[3] AVCLevelIndication
- 3); // 4 bytes length before each NAL unit
- if (m_videoId == MP4_INVALID_TRACK_ID)
- {
- printf("add video track failed.\n");
- return false;
- }
- MP4SetVideoProfileLevel(hMp4File, 0x01); // Simple Profile @ Level 3
- // write sps
- MP4AddH264SequenceParameterSet(hMp4File,m_videoId,lpMetadata->Sps,lpMetadata->nSpsLen);
- // write pps
- MP4AddH264PictureParameterSet(hMp4File,m_videoId,lpMetadata->Pps,lpMetadata->nPpsLen);
- return true;
- }
- int MP4Encoder::WriteH264Data(MP4FileHandle hMp4File,const unsigned char* pData,int size)
- {
- if(hMp4File == NULL)
- {
- return -1;
- }
- if(pData == NULL)
- {
- return -1;
- }
- MP4ENC_NaluUnit nalu;
- int pos = 0, len = 0;
- while (len = ReadOneNaluFromBuf(pData,size,pos,nalu))
- {
- if(nalu.type == 0x07) // sps
- {
- // 添加h264 track
- m_videoId = MP4AddH264VideoTrack
- (hMp4File,
- m_nTimeScale,
- m_nTimeScale / m_nFrameRate,
- m_nWidth, // width
- m_nHeight, // height
- nalu.data[1], // sps[1] AVCProfileIndication
- nalu.data[2], // sps[2] profile_compat
- nalu.data[3], // sps[3] AVCLevelIndication
- 3); // 4 bytes length before each NAL unit
- if (m_videoId == MP4_INVALID_TRACK_ID)
- {
- printf("add video track failed.\n");
- return 0;
- }
- MP4SetVideoProfileLevel(hMp4File, 1); // Simple Profile @ Level 3
- MP4AddH264SequenceParameterSet(hMp4File,m_videoId,nalu.data,nalu.size);
- }
- else if(nalu.type == 0x08) // pps
- {
- MP4AddH264PictureParameterSet(hMp4File,m_videoId,nalu.data,nalu.size);
- }
- else
- {
- int datalen = nalu.size+4;
- unsigned char *data = new unsigned char[datalen];
- // MP4 Nalu前四个字节表示Nalu长度
- data[0] = nalu.size>>24;
- data[1] = nalu.size>>16;
- data[2] = nalu.size>>8;
- data[3] = nalu.size&0xff;
- memcpy(data+4,nalu.data,nalu.size);
- if(!MP4WriteSample(hMp4File, m_videoId, data, datalen,MP4_INVALID_DURATION, 0, 1))
- {
- return 0;
- }
- delete[] data;
- }
- pos += len;
- }
- return pos;
- }
- int MP4Encoder::ReadOneNaluFromBuf(const unsigned char *buffer,unsigned int nBufferSize,unsigned int offSet,MP4ENC_NaluUnit &nalu)
- {
- int i = offSet;
- while(i<nBufferSize)
- {
- if(buffer[i++] == 0x00 &&
- buffer[i++] == 0x00 &&
- buffer[i++] == 0x00 &&
- buffer[i++] == 0x01
- )
- {
- int pos = i;
- while (pos<nBufferSize)
- {
- if(buffer[pos++] == 0x00 &&
- buffer[pos++] == 0x00 &&
- buffer[pos++] == 0x00 &&
- buffer[pos++] == 0x01
- )
- {
- break;
- }
- }
- if(pos == nBufferSize)
- {
- nalu.size = pos-i;
- }
- else
- {
- nalu.size = (pos-4)-i;
- }
- nalu.type = buffer[i]&0x1f;
- nalu.data =(unsigned char*)&buffer[i];
- return (nalu.size+i-offSet);
- }
- }
- return 0;
- }
- void MP4Encoder::CloseMP4File(MP4FileHandle hMp4File)
- {
- if(hMp4File)
- {
- MP4Close(hMp4File);
- hMp4File = NULL;
- }
- }
- bool MP4Encoder::WriteH264File(const char* pFile264,const char* pFileMp4)
- {
- if(pFile264 == NULL || pFileMp4 == NULL)
- {
- return false;
- }
- MP4FileHandle hMp4File = CreateMP4File(pFileMp4,352,288);
- if(hMp4File == NULL)
- {
- printf("ERROR:Create file failed!");
- return false;
- }
- FILE *fp = fopen(pFile264, "rb");
- if(!fp)
- {
- printf("ERROR:open file failed!");
- return false;
- }
- fseek(fp, 0, SEEK_SET);
- unsigned char *buffer = new unsigned char[BUFFER_SIZE];
- int pos = 0;
- while(1)
- {
- int readlen = fread(buffer+pos, sizeof(unsigned char), BUFFER_SIZE-pos, fp);
- if(readlen<=0)
- {
- break;
- }
- readlen += pos;
- int writelen = 0;
- for(int i = readlen-1; i>=0; i--)
- {
- if(buffer[i--] == 0x01 &&
- buffer[i--] == 0x00 &&
- buffer[i--] == 0x00 &&
- buffer[i--] == 0x00
- )
- {
- writelen = i+5;
- break;
- }
- }
- writelen = WriteH264Data(hMp4File,buffer,writelen);
- if(writelen<=0)
- {
- break;
- }
- memcpy(buffer,buffer+writelen,readlen-writelen+1);
- pos = readlen-writelen+1;
- }
- fclose(fp);
- delete[] buffer;
- CloseMP4File(hMp4File);
- return true;
- }
- bool MP4Encoder:: PraseMetadata(const unsigned char* pData,int size,MP4ENC_Metadata &metadata)
- {
- if(pData == NULL || size<4)
- {
- return false;
- }
- MP4ENC_NaluUnit nalu;
- int pos = 0;
- bool bRet1 = false,bRet2 = false;
- while (int len = ReadOneNaluFromBuf(pData,size,pos,nalu))
- {
- if(nalu.type == 0x07)
- {
- memcpy(metadata.Sps,nalu.data,nalu.size);
- metadata.nSpsLen = nalu.size;
- bRet1 = true;
- }
- else if((nalu.type == 0x08))
- {
- memcpy(metadata.Pps,nalu.data,nalu.size);
- metadata.nPpsLen = nalu.size;
- bRet2 = true;
- }
- pos += len;
- }
- if(bRet1 && bRet2)
- {
- return true;
- }
- return false;
- }